Production of metal carbonyls



Jan. 23, 1934. SCHLECHT El AL PRODUCTION OF METAL CARBONYLS Filed March 9, 1932 MA TERI/1L REACT/0N /CHAMBE/? EXHAUSTED MATERIAL REACTED GAS B C0 M T N C M R 8m 0 v.lu n m a A 3 .LMWM

BY via Patented Jan. 23, 1934 'UNETEQ STATES PATENT FFEQE PRODUCTION OF METAL CARBONYLS Application March 9, 1932, Serial No. 597,752, 7 and in Germany March 13, 1931 8 Claims.

The present invention relates to improvements in the production of metal carbonyls.

In the production of metal carbonyls by the action of carbon monoxide on material capable of forming carbonyls in continuous operation, the procedure hitherto followed has either been that the initial material, made into a paste with liquids or melts, is pumped continuously through the reaction chamber or that the reaction mate- 'j rials are introduced in a granular or pulverized form through a sluice and then led in thin layers, if desired over plates, grates, conveyor bands or sheets, through the reaction chamber, the residue being withdrawn also through a sluice.

We have now found that in the production of metal carbonyls special advantages are obtained when the initial material is continuously introduced into and the residue continuously withdrawn from the reaction chamber, while keeping 31 the whole reaction chamber at all times completely filled with the solid reacting material, whereby hollow spaces in the reaction vessel, which are greater than the intermediate spaces between the single particles of the solid material are substantially avoided. During the formation of the carbonyls, the material becomes more compact as the metal is used up and the volume occupied thereby becomes smaller; according to the present invention, however, the advantage is attained that the space thus set free is immediately filled again by freshly introduced material. The maximum throughput of reaction material attainable and therefore the yield of carbonyl per unit of time is much greater according to'the present invention than by the processes hitherto known, if the period during which the material is present in the reaction chamber remains the same. Contrary to expectation, a sintering together or conglomeration of the solid material whereby the process would be rendered incapable of being carried out, does not take place. a

The nature of the invention will be further described with reference to the accompanying diagrammatic drawing, of which Figure l illustrates an arrangement of apparatus suitable for carrying out the process according to this invention, whereas Figure 2 illustrates a detail of a modified form of apparatus, but the invention 50 is not restricted to the particular arrangements shown.

According to Figure 1, carbon monoxide under a pressure of 200 atmospheres is caused to flow upwards through a reaction chamber h which is wholly filled with small pieces of carbonyl-forming material. Exhausted material is withdrawn at short intervals of time through .s sluice 8 arranged at the lower end of the reaction chamber h. The withdrawal is effected by first adjusting the sluice s to the same pressure 60. as the reaction chamber h through a pipe I, then opening the valve 12 and setting the conveyor worm t in operation. When the sluice s is filled, the conveyor worm t is stopped, the valve 1) closed and the pressure in the sluice 3 released so that the sluice s may be emptied through the valve 10. To replenish the material withdrawn and that used up by the reaction, fresh material is introduced in a similar manner at the top of thereaction chamber h by means of a sluice 1', valves r and y and pipe m. The height to which the reaction chamber h is filled is supervised by means of a level indicator (not shown). The material may also be introduced at the bottom for example by an arrangement similar to a pump, the residue then being withdrawn at the top. The period of time occupied when working as hereinbefore described by releasing the pressure on the sluices and emptying or filling the same, during which time no supply or withdrawal of material takes place, may be avoided by providing two sets of sluices which are operated alternately or by providing between the reaction chamber and the sluices a buffer vessel which is always under the same pressure as-the reaction vessel and into which the exhausted residue may be withdrawn continuously for example by means of a conveyor worm, or from which fresh material may be continuously supplied to the reaction chamber. Then, especially when the buffer vessels are not too small, more time is available for emptying and filling the sluices without the yield per unit of time and space being injuriously affected. Instead of sluices, injection apparatus working similarly to pumps, many types of which are known, may be used for example.

In order to facilitate the convenient sliding of the material through the reaction vessel, and to establish a uniform passage of the gas through the material, it is advantageous to employ the reaction material at least partly in a coarse form or in theform of granules the size of which at the top is substantially limited by the dimensions of the filling apparatus employed. Mav terials which are not too large in size and having for example an average size between 0.3 and 20 millimetres and which before the treatment with carbon monoxide have passed through a rotary tubular furnace, as for example for the purpose of reduction by means of carbonaceous materials, are especially suitable because the grains are then rounded and the material is capable of trickling or sliding readily. Material which is present entirely in the form of a powder may be mixed with coarse, if desired briquetted, material or supplied to the reaction chamber alternately therewith. If desired, additional materials which have a loosening effect and which facilitate the passage of gas, as for example rings or tubes which may consist for instance of clay, aluminium or copper may be mixed with the powder or supplied to the reaction chamber in alternate sequence with the powder.

The shape of the reaction chamber may be varied within wide limits. When working under comparatively low pressures, even wide containers with a comparatively slight height of column, as for example those of 1 metre height and lmetre in diameter, are suitable. Conical reaction vessels which become narrower in the direction of movement of the reaction material may be employed, but more advantageously containers which become wider in the direction of movement are used in order to facilitate the flow of the reaction materials. The cross section of the containers may be circular or of other shapes favorable for the radiation of heat, as for example rectangular; the inner surface of the walls should be so constructed, however, that the forward movement of the reaction materials is not hindered.

When working with vertical containers of great length, for example 6 metres or more, i. e.

with long columns of material, it may be preferable to subdivide the column of material one or more times by devices which support the material in order to avoid too great a mechanical pressure being exerted on the material in the lowest part of the containers. As shown in Figure 2 this may be effected by inserting in the container one or more transverse baflles a, having for example centrally arranged openings 0, if desired shaped like a funnel, through which the material falls, if necessary by movement with stirring arms 2). If several such supporting bafiles with stirring devices are present, it may be preferable to drive the devices serving to move the material with different efficiency so that stoppages or interruptions within the column are avoided and a uniform throughput is obtained. This is effected either by driving the separate devices at different speeds or, for example, by driving the separate devices at the same speed and power by a single shaft, the amounts of material moved being differed by differences in the constructiongas for example in the size of shape of the stirring arms. If the material is readily capable of sliding, mechanical devices may be entirely dispensed within some cases and it suffices to insert perforated baffles in order to avoid an undesirably large mechanical pressure of the high column of material on the lowest part of the containers.

Instead of, or in addition to, the subdivision of the reaction chamber, an undesirably great mechanical pressure of the material on the bottom may be avoided for instance by a certain arrangement of the reaction vessel, as for example by inclining the same. In cases when the inclination from the vertical is very great or when the flow of material is horizontal, care must be taken that the material is continuously rendered compact, so that it completely fills the reaction chamber, for example by introducing the fresh material under an excess of pressure by means of a suitable pump or an eflicient conveyor worm. In cases of very extensive reaction chambers which are arranged horizontally, it may be necessary to efiect the rendering of the material compact and thereby the filling of the chamber not only by the introduction of fresh material, but also by the insertion of several filling, pressing or promoting devices, as for example conveyor worms, at intervals throughout the reaction chamber.

The movement of the material in nearly horizontal, or horizontal reaction containers may be effected or assisted by causing the reaction container to rotate. In some cases, especially when working under pressure, not the container itself is caused to rotate, but one or more insertions, as for example tubes having not too strong walls and therefore being easily revolvable. In this case the inserted tubes, rotating if desired, at different speeds are kept filled with solid reaction material, while the container bears the pressure and is not moved.

The withdrawal of the heat of reaction may be effected for example in the usual manner by internal cooling with cooling tubes or cooling coils or by external cooling with cooling ribs, or cooling jackets or by means of gases led through the reaction chamber, preferably by the reaction gas itself.

The introduction and/ or withdrawal of the care bon monoxide or gases containing carbon mom oxide, which may be led in the same direction as, or in counter current to, the material, is preferably effected at several places in the reaction container. The gas is advantageously led in a cycle.

The process according to the present invention is particularly suitable for the production of the carbonyls of nickel and cobalt from initial mate rials containing these metals, though of course it may be used as well for the production of other metal carbonyls, as for example iron carbonyl.

What we claim is: v

1. The process of producing a metal carbonyl by the action of carbon monoxide on a material capable of forming a metal carbonyl in a closed reaction chamber, which comprises the steps of continuously withdrawing from the reaction chamber spent material and continuously introducing fresh material into the reaction chamber at a rate corresponding to the amount of material used up and the amount of spent material withdrawn, thereby keeping the reaction chamber at all times substantially completely filled with the material.

2. The process as claimed in claim 1 wherein the material capable of forming a metal carbonyl is at least partly in the form of granules.

3. The process of producing nickel carbonyl by the action of carbon monoxide on a material capable of forming nickel carbonyl in a closed reaction chamber, which comprises the steps of continuously withdrawing from the reaction chamber spent material and continuously introducing fresh material into the reaction chamber at a rate corresponding to the amount of material used up and the amount of spent material withdrawn, thereby keeping the reaction chamber at all times substantially completely filled with the material.

4. The process of producing cobalt carbonyl by the action of carbon monoxide on a material capable of forming cobalt carbonyl in a closed reaction chamber, which comprises the steps of continuously withdrawing from the reaction chamber spent material and continuously introducing fresh material into the reaction chamber at a rate corresponding to the amount of material used up and the amount of spent material withdrawn, thereby keeping the reaction chamber at all times substantially completely filled with the material.

5. The process of producing iron carbonyl by the action of carbon monoxide on a material capable of forming iron carbonyl in a closed reaction chamber, which comprises the steps of continuously withdrawing from the reaction chamber spent material and continuously introducing fresh material into the reaction chamber at a rate corresponding to the amount of material used up and the amount of spent material 

